A gas turbine generally includes a compressor section, a combustion section having a combustor and a turbine section. The compressor section progressively increases the pressure of a working fluid to supply a compressed working fluid to the combustion section. The compressed working fluid is routed through and/or around a fuel nozzle that extends axially within the combustor. A fuel is injected into the flow of the compressed working fluid to form a combustible mixture.
The combustible mixture is burned within a combustion zone to generate combustion gases having a high temperature, pressure and velocity. The combustion gases flow through one or more liners or ducts that define a hot gas path into the turbine section. Kinetic energy is extracted from the combustion gases via turbine rotor blades coupled to a rotor shaft, thus causing the rotor shaft to rotate. The rotor shaft may support operation of the compressor and/or may be coupled to a generator to produce electricity.
In order to balance overall emissions performance, certain combustor designs include multiple fuel injectors that are arranged around the liner and positioned generally downstream from the combustion zone. The fuel injectors generally extend radially through the liner to provide for fluid communication into the combustion gas flow field. This type of system is commonly known in the art and/or the gas turbine industry as Late Lean Injection (LLI) and/or as axial fuel staging.
In operation, a portion of the compressed working fluid is routed through and/or around each of the fuel injectors and into the combustion gas flow field. A liquid or gaseous fuel from the fuel injectors is injected into the flow of the compressed working fluid to provide a lean or air-rich combustible mixture which combusts as it mixes with the hot combustion gases, thereby increasing the firing temperature of the combustor without producing a corresponding increase in the residence time of the combustion gases inside the combustion zone. As a result, the overall thermodynamic efficiency of the combustor may be increased without sacrificing overall emissions performance.
Current systems for providing fuel from an external fuel source to the late lean fuel injectors comprise numerous fluid conduits and fluid couplings that extend within a casing that surrounds the combustor. As a result, designers must account for the additional space required within the casing to accommodate the required hardware. This may affect the overall size of the combustor and/or may negatively impact fluid flow profiles within the combustor. Therefore, an improved system for providing fuel to the combustor, particularly to the late lean fuel injectors would be useful.